JPS62231802A - Off-road pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance the drive comfortability of a vehicle with the use of low pressure type off-road pneumatic tires, by providing a reinforcing layer having several cords parallel with the equator plane on the radially outer side of a carcass layer, and by cutting these cord in the reinforcing layer at several positions 8 over the entire periphery thereof. CONSTITUTION:More than one of reinforcing layers 6 are arranged on the radially outer side of a carcass layer 4. Further, each cord layer 6 has several cords 7 laid parallel with the equator plane 5 of the tire, and these cords 7 are divided into several gropes which are cut at more than two positions 8 over the entire periphery. Further, these cutting positions 8 are selected with suitable phases in the circumferential direction thereof so that they are uniformly distributed. With this arrangement it is possible to enhance the drive comfortability of a vehicle, and to ensure the advantages of a low pressure tire.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention provides a tire tire having a reinforcing layer having a large number of cords substantially parallel to the tire equatorial plane on the radially outer side of the carcass layer. ! ! Related to pneumatic tires for ground running.

(Prior art) Tires for running on rough terrain, such as buggy tires, are generally 0.
A low internal pressure of 1 to 0-5 k, g/cm" is used and the carcass layer has a number of cords extending in the meridian direction or a number of cords extending in a direction at a slight angle to the meridian. In addition, many tires have a tread placed directly on the outside of the carcass layer in the radial direction. Therefore, compared to general automobile pneumatic tires, dimensions such as outer diameter, tire width, crown curvature radius, etc. due to changes in internal pressure are less likely to occur than in general automobile pneumatic tires. The degree of change in speed is large, and the changes in dimensions such as outer diameter, tire width, crown curvature radius, etc. due to changes in running speed are also large.
In order to solve these problems, the crown curvature radius of the tire when used with internal pressure is smaller than that set in the mold, making it difficult to obtain a flat or round shape, and making it difficult to maintain steering stability. Consider making the cord direction of the carcass layer at a large angle with respect to the meridian, or attaching two or more reinforcing layers with a cord angle of 20 degrees or more to the tire equatorial plane on the radial outside of the carcass layer. It will be done.

(Problem to be Solved by the Invention) However, since such an angled carcass layer or an angled reinforcing layer requires a thickness of 27i or more, it becomes very expensive and the tire rigidity becomes excessive. This has the problem of impeding ride comfort, which negates the advantage of pneumatic tires for rough terrain that are used at low internal pressures.

(Means for solving the problem) Such a problem is that a pneumatic rough terrain tire used at low internal pressure has a large number of cords substantially parallel to the tire equatorial plane on the radially outer side of the carcass layer. Place the reinforcement layer,
This problem can be solved by dividing each cord of the reinforcing layer at at least two points per circumference, and by setting the arrangement of these dividing points in various ways, a variety of pneumatic tires for rough terrain can be provided. be able to.

(Function) Since the many cords of the reinforcing layer are substantially parallel to the tire equatorial plane, a sufficient hoop tightening effect can be expected even with just one layer, and while it is inexpensive, it can prevent the growth of

Furthermore, by distributing these cord division points almost uniformly in the reinforcing layer, it is possible to obtain a tire rigidity that is almost uniform over the entire crown.

Furthermore, by setting a small number of parts where these cords are divided, it is possible to increase the tire rigidity, and by setting a large number of parts where these cords are parted, it is possible to lower the tire rigidity. can be obtained easily.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, ■ is a pneumatic tire for buggy vehicles, and this pneumatic tire l for rough terrain has a carcass layer 4 that is folded back at a pair of bead cores 2 and deformed into a toroidal shape. This carcass Nj4 has a large number of cords parallel to each other, and these cords intersect with the tire equatorial plane 5 at an inclined angle in the range of 90' or 80'' to 906. As shown in FIGS. 1 and 2, one or more layers (in this example, one layer) of reinforcement R6 are arranged on the radially outer side, and each reinforcement layer 6 has a large number of cords 7 substantially parallel to the tire equatorial plane. This cord 7 is divided into at least two places per circumference in units of several cords, and these divided points 8 are provided with an appropriate phase in the circumferential direction, so that the divided points 8 are separated from the reinforcing layer. They are almost uniformly distributed within the cord 7. At each dividing point 8 of the cord 7, a gap is formed between the divided ends of the cord 7 during the diameter expansion process of the tire being manufactured.

Such a pneumatic tire 1 is manufactured as follows. First, the carcass layer 4 is pasted on a tire molding drum to form the same cylindrical shape, then a pair of bead cores are driven in, and both ends of the carcass layer 4 are folded back around the bead core.
Expands in diameter toroidally. On the other hand, a large number of cords 7 parallel to the pressure are rubberized to form a rubberized cord layer,
Next, this rubberized cord layer is cut into a length approximately equal to one circumference of the toroidally expanded carcass M4.

At this stage, each hood 7 is cut together with the rubber at at least one place as shown in FIG. As a result, each cord is broken at at least two places, the chain breaking point and the above-mentioned cutting point. The cord 7 is divided in units of several cords, and the divided points 8 are provided with an appropriate phase,
They are randomly formed within the rubberized cord layer 21. In addition, in this example, the number of division points of each cord in the rubberized cord F3:21 is the same.The rubberized cord layer 21 is placed on the outside of the carcass layer 4 in the radial direction, and its both ends are As shown in FIG. 3, they are partially overlapped to form a joint 9 and pasted. At this time, since the rubberized cord calendar 21 is a single continuous band-shaped material and its shape is the same as the conventional one, it can be easily molded as in the conventional one.After pasting the tread 10 on the zeroth The diameter is further expanded in a toroidal shape in the vulcanization mold, but at this time, the cords 7 slip each other and the cord 7 at the #R point 8
A gap with a distance equal to the amount of change in the circumferential direction divided by the number of dividing points (the number of dividing points including the joint portion 9) is created, and a change in the radial direction, that is, an enlargement of the diameter is allowed. Vulcanization is performed in this state to produce a product tire. In this way, each cord of the reinforcing layer 6 is divided at at least two places per circumference, and since there is only one reinforcing layer, the tire rigidity is not very high, and it can be manufactured at a low cost and can be formed into a toroidal shape. It can also follow diameter changes. Furthermore, since each cord of the reinforcing layer 6 is substantially parallel to the tire equatorial plane, a sufficient hoop tightening effect can be expected. Here, each cord is divided at at least two places per circuit, so the cord itself cannot bear stress in the circumferential direction, but there is resistance to pulling out the cord and rubber and shearing resistance of the rubber between the cords. This serves a circumferential butt tightening function, and can suppress diameter growth due to speed changes, internal pressure changes, temperature changes, tread wear, etc.

In addition, the number of divisions of each cord is preferably 2 to 15, and more preferably 3 to 9.The reason is that if the number of divisions is less than 2, the cord will slip when expanding into a toroidal shape. This is because the gauge thickness of the tray 2 located on the radially outer side of the reinforcing layer 6 becomes too large and the gauge thickness of the tray 2 located on the outside in the radial direction of the reinforcing layer 6 partially fluctuates. Because it does.

Here, the number of divisions is defined as one cutting location and the number of division locations 8 added thereto. Note that it is preferable that the number of divisions be the same for each cord, but the radius of crown curvature can be increased by making the number of divisions in the cord located at the center of the crown smaller than the number of divisions in the cords located on both sides of the crown. is possible,
Conversely, by making the number of divisions in the central cord greater than in the cords on both sides, the radius of crown curvature can be made smaller.

Furthermore, this invention can be applied to tires for golf carts and agricultural waste.
It can also be applied to tires for land transport vehicles.

Attached Table 1 shows the specifications and test results of the pneumatic buggy tires used in the test. The ear size used for this test was 22X 11.00-8, and the applicable rim was 8X.
8.25, the internal pressure when measuring the change in outer diameter due to speed is 0
．． 15 kg/cm'. Change in outer diameter due to internal pressure (
%) is expressed as an index with the outer diameter at 0.15 kg/cm" as 100. As is clear from this test, this
In the tire of No. 1, the outer diameter change at high speeds can be sufficiently reduced with the minimum material, that is, one reinforcing layer, and the dimensional stability can also be significantly improved.

Furthermore, in Attached Table 1, (1) g! The results of a driver's feeling test in an actual vehicle are shown regarding comfort and (2) overall driving performance of handling and grip. Feeling test scores were measured on a 10-point scale from 10 (good) to 1 (bad).

(1) Ride comfort was evaluated based on the degree of softness during running. The overall driving performance (2) was evaluated by comprehensively evaluating two driving performances: handling performance based on the degree of ease of turning the steering wheel, and grip performance based on the degree of grip force on the road surface on rough terrain.

According to the present invention, it is possible to obtain a tire that does not significantly improve handling properties and grip properties, but also improves the tendency to be too soft, and provides a satisfactory ride comfort.

(Effects of the Invention) As explained above, according to the present invention, without reducing production efficiency and without increasing tire rigidity too much,
The outer diameter, width,
The dimensional stability of the crown curvature radius can be improved.

[Brief explanation of drawings]

Fig. 1 is a meridian cross-sectional view of a buggy river tire showing an embodiment of the present invention, Fig. 2 is a developed view of the reinforcing layer of the tire shown in Fig. 1, and Fig. 3 is an attachment of the reinforcing layer in Fig. 2. is the previous development. l... Pneumatic tire 4... Carcass layer 5... Tire equatorial plane 6... Reinforcement layer 7... Cords 8 and 9... Separation point 9... Joint portion Patent applicant Co., Ltd. Brideston Patent Attorney Hide Kume - Representative Patent Attorney Etsu Suzuki Part 1, No. 2 @, 5 8, -1 Division

Claims (4)

[Claims] (1) A carcass layer and a reinforcing layer having a large number of cords substantially parallel to the tire equatorial plane are disposed radially outward of the carcass layer, and each cord of the reinforcing layer is connected at least twice per circumference.
A pneumatic tire for rough terrain that is divided into parts and used at low internal pressure. (2) The pneumatic tire for rough terrain according to item 1, wherein the number of the dividing points is almost uniformly distributed within the reinforcing layer. (3) The air for rough terrain according to item 1, wherein the number of the dividing points in the cord of the reinforcing layer located in the center of the crown is smaller than the number of dividing points in the cord of the reinforcing layer located on both sides of the crown. Included tires. (4) A first method in which the number of the above-mentioned dividing points in the cord of the reinforcing layer located at the center of the crown is greater than the number of the above-mentioned dividing points in the cord of the reinforcing layer located on both sides of the crown.
Pneumatic tires for rough terrain as described in section.